1. Field of the Invention
This invention relates to interactive television systems and more particularly to the insertion of interactive program content within a television signal originating at a remote network.
2. Description of the Relevant Art
The emerging technology of interactive television holds a promise of allowing a television set to serve as a two-way information distribution mechanism. Proposed features of interactive television accommodate a variety of marketing, entertainment and educational capabilities such as allowing a user to order an advertised product or service, compete against contestants in a game show, or request specialized information regarding a televised program. Typically, the interactive functionality is controlled by a "set top" decoder which executes an interactive program written for the television broadcast. The interactive functionality is often displayed upon the television's screen and may include icons or menus to allow a user to make selections via the television's remote control.
Several unique problems are posed for a digital broadcaster of interactive television, particularly for configurations involving "turn arounds". The term "turn around" refers to a configuration in which a video feed originating at a remote network comes into the digital broadcast plant. The video feed from the remote network is often in an analog format and may be a live telecast. When the video feed is received at the digital broadcast plant, it is demodulated or decoded and converted into the native format of the digital broadcast plant. One such native format is SMPTE-259M, which is a 270 Mbps digital studio standard. The native video signal is routed throughout the broadcast plant, possibly taped and time shifted, and is subsequently routed to a video encoder where it is compressed and retransmitted. For the vast majority of broadcasts, the content does not reside within the digital broadcast plant for more than several hundred milliseconds.
If a digital broadcaster desires to add interactive functionality to a television signal originating at a remote network, the interactive programming information must be inserted at the proper time. However, present practices are such that the digital network operator does not need, nor have, elaborate information regarding the content playing on the turn around channel. Although there is sufficient information to build a program guide indicating the approximate times of the airings of specific programs, there is not sufficient information to determine exactly when a particular program will begin, when commercials will be played, and whether certain preemptive actions have been taken. This information remains with the program originator, which is geographically remote and typically operated as a separate business.
To complicate the problem still further, the order of playing interactive content and the ability to invoke "day of air" edits should be controlled by the signal originator. Although the interactive programming information could be provided directly by the signal originator, most remote networks are neither equipped to provide interactive programming nor have suitable transmission formats and bandwidth to allow for interactive content. In addition, it is often desirable that the digital broadcaster be able to maintain control over the actual airing and content of the interactive programming, which is typically not possible or practical if the interactive programming information is provided directly by the signal originator.
An interactive television system may thus be configured such that commands are sent from a remote network to a broadcast station where the interactive content is actually combined with the television signal. A problem can occur within such a configuration, however, if the command from the remote network is for some reason not received at the broadcast station, or is otherwise corrupted in the transmission. If such a failure occurs, the interactive program content will not play in accordance with the commands from the remote network. A protocol and system for transmitting commands from a remote network and for controlling interactive program content at a broadcast station are thus desirable which alleviate the problems of failed command transmissions from the remote network.